The 5:30 PM the first night is just a place holder time. I have never heard of them having the chef's table the first night.
They have a wine pairing that they offer at the chef's table. There is an extra charge. If you do not want the pairings, and you have a beverage package, you can use that at the chef's table.
Most of the time, the executive chef on the cruise will head up the chef's table. There would be a small likelihood of Boulud being on the cruise, but it could happen.
I hope this is of some help to you. 🙂